[Relativity FAQ] - [Copyright]

original by Siegmar Schleif 17-Jan-1998

What is the experimental basis of the Special Relativity Theory?

Physics, as a natural science, is based on empirical facts. Physical theories cannot be based just on speculation or suspicion. On the other hand it is always reasonable to have doubts concerning established theories. Reading the posts in sci.physics.relativity I have got the impression, that the huge experimental support for this theory is sometimes not well known. The list of experiments below shows that the SRT is really tested very well. Hypotheses which claim, that SRT is just "wrong" have to show that all the experiments mentioned below had errors or that their interpretation is not correct.

There is a lot of redundancy in these experimental tests. There are also a lot of indirect tests of SRT which are not included in the list shown below. This list of experiments is NOT complete! I cannot guarantee, that the literature list has no mistakes. If I get a positive feedback, I am willing to update the list shown below and to correct all possible errors.

For those seriously concerned about this subject there is an essential new reference book: "Special Relativity and its Experimental Foundation" by Yuan Zhong Zhang, World Scientific (1996).


Prelude: Special Relativity and Experiments
I. Basic (Classic) experiments concerning SRT
II. Repetitions of the MMX
III. Repetitions of the Fizeau experiment
IV. Repetition of the Trouton-Noble experiment
V. Sagnac Effect
VI. Repetition of the KTX
VII. Speed of Light independent of the velocity of the source
VIII. Isotropy of Space: Hughes Drever Experiments
IX. Isotropy of the Speed of Light
X. Relativistic Mass-Energy Relation
XI. Transversal Doppler effect
XII. Time Dilatation, Clock "paradox"
XIII. Some other Experiments

Special Relativity and Experiments

The Special Theory of Relativity (SRT) is a theory which was invented to explain several experimental results. SRT is NOT a mathematical game or just a hypothesis. SRT is a theory which has been well tested several times.

When A. Einstein wrote his famous paper: "The Electrodynamics of Moving Bodies" he already had experimental support for the new theory:
".... Examples of this sort, together with the unsuccessful attempts to discover any motion of the Earth relatively to the "light medium" suggest that the phenomena of electrodynamics as well as of mechanics possess no properties corresponding to the idea of absolute rest. They suggest rather that, as has already been shown to the first order of small quantities, the same laws of electrodynamics and optics will be valid for all frames of reference for which the equations of mechanics hold good..."

What was the experimental support for this claim?

1. There were several experiments concerning the electrodynamics of moving bodies, which are not very well known today, but Einstein knew this experiments:

2. In addition there were two experiments concerning the effect of the motion of the Earth concerning the double refraction:

3.Important experiments which influenced Einstein were the experiments of Arago, Fizeau and Hoek. This experiments alone set very stringent constrains to several ether theories, which was shown by Lorentz in 1885.

Robertson has shown in 1949 ( Review of Modern Physics 21, p. 378) that one can unambiguously deduce SRT with the following three experiments

  1. Michelson-Morley
  2. Kennedy-Thorndyke
  3. Transversal Doppler Effect

I. Basic (Classic) experiments concerning SRT:

0: Arago
1: Fizeau
2: Hoek
3: Michelson-Morley
4: Trouton-Noble
5: Kennedy-Thorndyke
6: Sagnac
7: Michelson-Gale

These experiments are described in nearly every basic physics book about the Special Theory of Relativity:

French: Special Relativity (Chapman and Hall 1968)
Sommerfeld: Theoretical Physics Vol 3 and 4
Born: The Theory of Relativity
Bergmann-Schaefer (in German)
von Laue ( in German)
Taylor Wheeler: Space-time Physics

Original Sources:

MMX : A.A. Michelson and E.W. Morley, On the Relative Motion of the Earth and the Luminiferous Ether Am. J.Sci. (3rd series) 34 333-345 (1887).

Discussion of the MMX experiment, the Fizeau experiment and the repetition of the Fizeau experiment by Michelson and Morley is given in: Shankland, American Journal of Physics 1964, p.16

KTX: R.J. Kennedy and E.M. Thorndike, Experimental Establishment of the Relativity of Time Phys. Rev. 42 400-418 (1932)

II. Repetitions of the MMX:

  1. G. Joos, Ann. Phys. 7 385 (1930)
  2. R.S. Shankland, S.W. McCuskey, F.C. Leone and G. Kuerti, New Analysis of the Interferometric Observations of Dayton C. Miller, Rev. Mod. Phys. 27 167-178 (1955)
    This Publication gives a table of the results of Michelson Morley experiments between 1880 and 1930:
    Name Year Arm length of the interferometer Fringe shift expected Fringe shift measured
    Michelson 1881 1.2 0.04 0.02
    Michelson + Morley 1887 11.0 0.4 0.01
    Morley + Morley 1902-04 32.2 1.13 0.015
    Miller 1921 32.0 1.12 0.08
    Miller 1923-24 32.0 1.12 0.03
    Miller (Sunlight) 1924 32.0 1.12 0.014
    Tomascheck (Starlight) 1924 8.6 0.3 0.02
    Miller 1925-26 32.0 1.12 0.088
    Kennedy (Mt. Wilson) 1926 2.0 0.07 0.002
    Ilingworth 1927 2.0 0.07 0.0002
    Piccard + Stahel(Mt.Rigi) 1927 2.8 0.13 0.006
    Michelson et al. 1929 25.9 0.9 0.01
    Joos 1930 21.0 0.75 0.002
  3. T.S. Jaseja, A. Javan, J. Murray and C.H. Townes, Test of Special Relativity or of the Isotropy of Space by Use of Infrared Masers Phys. Rev. 133A 1221-1225 (1964)
  4. A. Brillet and J.L. Hall, Improved Laser Test of the Isotropy of Space Phys. Rev. Lett. 42 549-552 (1979)

III. Repetitions of the Fizeau experiment:

  1. Michelson-Morley,: American Journ. Science 31, 377 (1886)
    Repetition of Fizeau's experiment, NOT the original MMX experiment!
  2. Zeeman: Proc. Royal Soc. Amsterdam 17, p. 445 (1914)
    Proc. Royal Soc. Amsterdam 18, p. 398 (1915)
    Amst. Versl. 23, p. 245 (1914)
    Amst. Versl. 24, p. 18 (1915)

    A critical review of Zeeman's experiments is presented by
    Lerche, American Journal of Physics Vol. 45, p. 1154 (1977)
  3. Journal of Applied Physics 35, p. 2556 (1964)

IV. Repetition of the Trouton-Noble experiment:

Chase, Physical Review 28, p. 378 (1926)

V. Sagnac Effect:

Summary article in Review of Modern Physics Vol 39, p. 475 (1962)

VI. Repetition of the KTX:

Hils and Hall, Physics Review Letter 64, p. 1697

VII. Speed of Light independent of the velocity of the source:

Koninklijke Akademie van Wetenschappen, vol 15, part 2, p.1297-1298 (1913)
Koninklijke Akademie van Wetenschappen, vol 16, part 1, p.395 - 396 (1913)
written by de Sitter It is not difficult to get these papers. They are available via WWW:

This experiment was criticized by
J.G. Fox Am. Journal of Physics 30,297 (1962); 33, 1 (1964)


  1. Alvager F.J.M. Farley, J. Kjellman and I Wallin, Physics Letters 12, 260 (1964)
  2. Babcock and Bergmann, Journal Opt. Soc. Amer. Vol. 54, p. 147 (1964)
  3. Filipas and Fox, Phys. Rev. 135, 1071 B (1964)
  4. K. Brecher, Is the Speed of Light Independent of the Velocity of the Source? Phys. Rev. Lett. 39 1051-1054, 1236(E) (1977)

VIII. Isotropy of Space: Hughes Drever Experiments ( very accurate, best test!)

  1. Hughes et al., Physics Review Letters 4, 342
  2. Drever, Philosophical Mag. 6, 683
  3. Prestage et al., Physics Review Letters 54, 2387 (1985)
  4. Lamoreaux et al., Physics Review Letters 57, 3125 (1986)
  5. Chupp et al., Physics Review Letters 63, 1541 (1989)

IX. Isotropy of the Speed of Light:

  1. Cedarholm, Havens, Towens, Physics Review Letters 1, p. 342
  2. Trimmer et al., Physics Review D Vol. 8, p. 3321 (1973)
    and Physics Review D Vol 9, p. 2489 (1974)
  3. Riis et al., Physics Review Letters 60, p. 81 (1988)
  4. Krisher et al., Physics Review Letters 64, p. 1322 (1990)

X. Relativistic Mass-Momentum Relation:


  1. W Kaufmann, "Uber die Konstitution des Elektrons" Ann. Physik 19 ,495 (1906) ( first historical experiment)
  2. W. Kaufmann, "Uber die Konstitution des Elektrons", Sitzungsberichte der preussichen Akademie der Wissenschaften, 1915, Part 2.
    There were several discussions about the conclusions from Kaufmann's experiments and his data analysis. This was discussed in references 3 and 4 by M.Planck:
  3. M. Planck, "Die Kaufmannschen Messungen der Ablenkbarkeit der beta-Strahlen in ihrer Bedeutung fur die Dynamik der Electron", Verhandlungen der Deutschen Physikalischen Gesellschaft, 8, 1906.
  4. M. Planck, "Nachtrag zu der Besprechung der Kaufmannschen Ablenkungsmessungen", Verhandlungen der Deutschen Physikalischen Gesellschaft, 9, 1907.
  5. A.H. Bucherer, Phyz. Zeitschr. 9 (1908), p. 755; Ber. d. deutschen Phys. Ges. 6 (1908), p. 688.
    A. Bucherer, "Die experimentelle Bestatigung des Relativitatsprinzips", Annalen der Physik, 28, 1909.
  6. E. Hupka, Ann. Phys. 31 (1910), p. 169.
  7. Cl. Schaefer and G. Neumann, Phys. Zeitschr. 14 (1913), p. 1117.
  8. Ch.E. Guye and Ch. Lavanchy, Comptes rendus 161 (1915), p. 52.
  9. Rogers et al. Physical Review 57, p. 379
  10. Meyer et al. Helv. Physica Acta 36 , p. 981 (1963)
  11. W. Bertozzi in Am. J. Phys. 32, 551 (1964)


Zrelov, Tiapkin, Farago Soviet Physics JETP, Vol.34, p.384 (1958)

Description and Outline of experiments for education :
W. Bertozzi, Am. J. Phys. 32, 551 (1964)

XI. Transversal Doppler effect:

  1. H.E. Ives and G.R. Stilwell, An Experimental Study of the Rate of a Moving Atomic Clock J. Opt. Soc. Am. 28 215-226 (1938)
    An Experimental Study of the Rate of a Moving Atomic Clock. II J. Opt. Soc. Am. 31 369-374 (1941)
  2. Otting, Physik. Zeitschr. 40 , 681 (1939)
  3. Hay, Schiffer et al. Physics Review Letters 4 , p. 165 (1960)
  4. Mandelberg and Witten: Journal Opt. Soc. Amer. 52, p. 529 (1962)
  5. Kuendig: Physical Review 129, p. 2371 (1963)
  6. Champeney, Isaak and Khan: Proc. Physical Soc. Vol. 85, p. 583 (1965)
  7. Olin et al.: Physical Review D , Vol. 8, p. 1633
  8. M. Kaivola, O. Poulsen, E. Riis and S.A. Lee, Measurement of the Relativistic Doppler Shift in Neon, Phys.Rev. Lett. 54 255-258 (1985)
  9. Zeitschrift fuer Physik A 342, p. 455 (1992)
  10. McGowan et al. , Physics Review Letters 70, p. 251 (1993)

XII. Time Dilatation, Clock "paradox":

Four experimental types can be distinguished:

A: One way experiments:

  1. Muons: Rossi and Hoag, Physical Review 57, p. 461 (1940)
    Rossi and Hall, Physical Review 59, p. 223 (1941)

    Lifetime measured at rest :
    Rasetti, Physical Review 60, p. 198 (1941)
    (first historical experiments)
  2. Pions: Durbin, Loar and Havens, Physical Review 88, p. 179 (1952)
  3. D. Frisch and J. Smith, Measurement of the Relativistic Time Dilation Using Mesons Am. J. Phys. 31 (1963) 342.
    A good interpretation was given by :
    Terell, Nuovo Cimento 16 (1960) p. 457

B: Experiment using the Moessbauer effect:

Pound Rebka, Physics Review Letters 4, p. 274
Theoretical interpretation:
Josephson, Physics Review Letters 4, p. 341

C: Round trip experiments using elementary particles:

  1. Older Experiments ( lower Gamma-Factor):
    Farley et al., Nuovo Cimento Vol 45, p. 281 (1966)
    together with Farley et al., Nature 217, p. 17 (1968),
    Nuovo Cimento 9A, p. 369 (1972)
  2. Bailey et al., "Measurements of relativistic time dilatation for positive and negative muons in a circular orbit," Nature 268 (July 28, 1977) p. 301.
    More details about this experiment can be found in:
    Nuclear Physics B 150 p.1-79 (1979)
    Measurement of the Muon lifetime at rest:
    Meyer et al., Physical Review 132, p. 2693
    Balandin et al. JETP 40, p. 811 (1974)
    Bardin et al. Physics Letters 137B, p. 135 (1984)

D: Experiments with macroscopic clocks:

  1. Vessot, R.F.C. and Levine, M.W. 1979, "A Test of the Equivalence Principle Using a Space-borne Clock," Gel. Rel. Grav., 10, 181-204.
    Vessot, R.F.C et.al., 1980, "Test of Relativistic Gravitation with a Space borne Hydrogen Maser" Phys. Rev. Lett. 45 2081-2084.
  2. Haefele-Keating Experiment: Around-the-World Atomic Clocks
    Proposal: J. Haefele, Nature 227 (1970), p. 270
    Experiment: Science Vol. 177 p. 166 - 170 (1972)
    Here are the numbers from the Haefele-Keating experiment:
    DELTA T in nanoseconds
    Eastward Westward
    Clock 120 -57 277
    Clock 361 -74 284
    Clock 408 -55 266
    Clock 447 -51 266
    Predicted -40 +/-23 275 +/-21

    Prediction means: Sum of GR effect + SR effect
    With their "fit method" ( taking into account the clock drifts) H&K get:
    East : -66 nsec West : 205 nsec
    This agrees well with the average values ( second method) of
    East : -59 +/- 10 nsec West : 273 +/- 7 nsec

  3. 273 +/- 7 nsec C. Alley:
    "Proper Time Experiments in Gravitational Fields with Atomic Clocks, Aircraft, and Laser Light Pulses," in Quantum Optics, Experimental Gravity, and Measurement Theory, eds. Pierre Meystre and Marlan O. Scully, Proceedings Conf. Bad Windsheim 1981, 1983 Plenum Press New York, ISBN 0-306-41354-X

XIII. Some other Experiments

Calorimetric test of special relativity:
D.R. Walz, H.P. Noyes and R.L. Carezani, Physical Review A29 (1984), p. 2110

Test of special relativity by a determination of the Lorentz limiting velocity:
Does E=mc2?
G.L. Greene et al., Physical Review D 44 (1991) R2216

Other experiments which show the limiting velocity c with Neutrinos:

  1. Electron-Neutrinos : Physics Letters 201 ,p. 353 (1988)
    using Neutrinos from the Supernova SN 1987A
  2. Muon-Neutrinos:
    ALSPECTOR, Physics Review Letters 36, p.837 (1976)
    Kalbfleisch et al., Physics Review Letters 43, p.1361 (1979)

g-2 experiments as a test of special relativity:

  1. F. Combley et al., Physical Review Letters 42 (1979), p. 1383
  2. P.S. Cooper et al,. Physical Review Letters 42 (1979), p. 1386